Film having fine voids and manufacture thereof
US6004664A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 6, 1998 |
| Grant date | Dec 21, 1999 |
| Priority date | — |
| Expiry date | Jul 6, 2018 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/249979
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A polyester film having fine voids, which comprises a polymer mixture comprising a polyester resin and a thermoplastic resin (B) incompatible with said polyester resin, and which has an apparent specific gravity of 0.6-1.3 and an inplane birefringence as determined from the equation: EQU inplane birefringence=refractive index along lengthwise principal axis-refractive index along crosswise principal axis, of from -0.02 to +0.04, and manufacture thereof. A thermoplastic resin film having fine voids, which comprises a polymer mixture comprising a thermoplastic resin (A) and a thermoplastic resin (B) incompatible with said thermoplastic resin (A), and which has a ratio (L1/L2) of an average length (L1) of the voids at a cross section in the lengthwise direction of the film, to an average length (L2) of the voids at a cross section in the direction forming a right angle with said lengthwise direction, i.e., crosswise direction of the film, of 2/3-3/2, a thickness variation of the film of not more than 5%, and a void content of 5-50% by volume, and manufacture thereof. The polyester film having fine voids of the present invention has an extremely superior isotropy, excellent tear resist…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.